1. Field of the Invention
The present invention relates to a rotary cutter for cutting a continuous corrugated strip into strip sections having variable lengths. More particularly, this invention is applicable to a rotary cutter for shearing a metallic corrugated strip into sections which are used as corrugated fins in the manufacture of automobile radiators.
2. Description of the Related Art
Certain types of automotive radiator cores include corrugated fins welded or soldered to water tubes. Corrugated fins are obtained by passing a continuous metallic strip between a pair of toothed forming rollers or wheels to form a continuous corrugated strip, which is then sheared by a cutting machine into sections having a desired length. For the manufacture of radiators on a mass production basis, it is desirable for a cutting machine to operate at as high a speed as possible to shear a corrugated strip discharged continuously and at a high speed from the forming rollers. Another requirement for a cutting machine is the capability of shearing the corrugated strip into a desired length, which may vary depending upon the size of the radiator cores to be manufactured. A further requirement is to cut the corrugated strip precisely at a desired shearing point in order to obtain a series of strip sections having a uniform length.
U.S. Pat. No. 4,480,456 issued to Iwase et al. illustrates an example of a conventional cutting machine of the flying shear type which is adapted to cut a continuous corrugated strip into strip sections usable in radiator cores. The cutting machine includes a reciprocating carriage which is driven for reciprocating movement along the continuous corrugated strip emerging from the forming rollers. The carriage has mounted thereon a movable cutter blade of the guillotine type that cooperates with an associated fixed cutter blade on the carriage to shear the strip at the nadir of a corrugation. To perform shearing, the carriage is accelerated to move in synchronization with the moving strip and the movable cutter blade is then activated. Thereafter, the carriage is returned to the original position in order to be ready for the next shearing. The processing speed of this machine is limited due to the fact that the carriage, having a considerable inertia mass, must be reciprocated every time shearing is effected. Another problem arises when the processing speed of the machine is changed in order for the cutting machine to be switched over from an operational mode, wherein a series of strip sections having a given length are produced, to another mode wherein another series of strip sections having different length are to be manufactured. It has been found that, in conventional reciprocating cutting machines, it is difficult to make the carriage speed follow the change in the processing speed, thereby failing to effect shearing exactly at the nadir of a corrugation and to produce strip sections having a uniform length immediately after the change in the operational mode.